Isotat for the treatment of materials in liquid

ABSTRACT

The invention relates to the equipment for high-pressure, high-temperature treatment of materials in liquid and enables to broaden the technological capabilities of an isostatic press. The isostatic press for treatment of materials in liquid comprises a multi-cylinder pressure vessel forming a hermetically sealed working chamber connected to a gas source. The open-top container for liquid is placed in the working chamber in such a way that a gap is created between the inner wall of the pressure vessel and the outer wall of the container. The container with the liquid and the treated material is placed on an electrically insulated heater which, in its turn, is mounted on a protective magnetic block.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of Russian ApplicationNo. 99123273 filed Nov. 10, 1999. Applicant also claims priority under35 U.S.C. §120 of PCT/RU00/00148 filed Apr. 25, 2000. The internationalapplication under PCT article 21(2) was not published in English.

FIELD OF THE INVENTION

Invention relates to the equipment for treatment of materials in aliquid under high pressures and temperatures and can be used mostefficiently in curing, polymerization, densification and chemicaltreatment of discrete and continuous materials under pressures above.The 10 MPa and temperatures above 100° C.

BACKGROUND OF THE INVENTION

Isostatic pressing technology is considered as one of the “hightechnologies” and is rapid developing in the world.

There is a known isostatic press (see the prospectus of VNIIMETMASH“Machines for Powder Metallurgy”, published in Moscow by Vneshtorgizdat,1990, edition No. 763MB, p.5) that includes a pressure vessel with aworking chamber.

The working chamber is hermetically sealed by the top and bottomclosures that form a closed hermetic work volume in which the treatedproduct is placed.

The treatment of the product is achieved by feeding the working liquidunder the required pressure into the vessel.

The shortcoming of this isostatic press is that the process takes placeat the ambient temperature since, owing to its design's peculiarity, itcannot be equipped with a heater. The cause of it is that the vessel isfilled with a liquid. This reduces the technological capabilities ofsuch press.

Moreover, the working liquid itself, by acting on the treated product,gets into direct contact with the inner walls of the pressure vessel andcauses their corrosion. All this has a negative effect both on thequality of the treated product and on the durability of pressure vesseldue to the aggressive influence of the applied liquid on the innersurface of the pressure vessel. In some cases such influence leads toleakage and, furthermore, to the liquid's breaking through into theworking medium and its contamination.

The closest to the claimed invention is the cold isostatic press fortreatment of materials in liquid (see the prospectus of ASEA, Sweden,A08-4007E, 1990, p. 3) which comprises a multi-cylinder pressure vesselwith coaxial tightly fitted one-piece metal cylinders, whereof the outercylinder has a tightly wound flat steel wire on its surface and theinner cylinder forms a working chamber which is hermetically closed bythe top and bottom closures with seals and connected to a liquid sourcethat creates a pressure in the vessel. The working liquid is fed underpressure directly into the vessel where the treated product is placed.

This prototype cold isostatic press has the same shortcomings as the onedescribed before. Moreover, the liquid leakage from the vessel causes arapid pressure drop in it (due to small compressibility of the liquid)which leads to disruption of the normal technological process.

SUMMARY OF THE INVENTION

The claimed invention is aimed at expanding the technologicalcapabilities of isostatic pressing in isostatic presses.

The technical result of the claimed invention consists in making use ofthe advantages of a gas as a pressure-creating medium while subjectingthe product to the action by a liquid. Both gas (mainly inert gas) andspecially chosen liquids are used as working medium. Thereby thetreating (forming) effect on the product is achieved by the liquid andthe pressure is conveyed to the liquid through the gas medium. Owing tohigh compressibility of the gas medium, the pressure in the vessel isfalling not so intensively during gas leakage than when a liquid is usedas a pressure medium. Overall power consumption is lowered, theenvironmental effect is improved, the materials consumption and thedimensions of the apparatus in general are reduced.

The technical result is achieved as the isostatic press for treatment ofmaterials in a liquid, comprising a pressure vessel which forms ahermetically sealed working chamber connected to the pressure sourcewherein an open-top container for liquid is placed in such a way that agap between the inner wall of the pressure vessel and the outer wall ofthe container for liquid is created, whereby the container for liquidhas a hermetically sealed bottom made of a current-conducting materialand is placed on an electrically insulated inductive heater mounted onthe protective magnetic block, while the pressure source is a gassource.

Thereby the pressure vessel is preferably made as a multi-cylinder unitwith coaxial tight-fitting one-piece metal cylinders, whereof the outercylinder is made with a tightly wound prestressing flat steel wire andthe working chamber is hermetically sealed by the top and bottomclosures with seals.

Thereby the protective magnetic block is located on the upper butt ofthe bottom closure.

Thereby the apertures for inlet-outlet of cooling water can be made onthe surface of one of the one-piece metal cylinders forming the pressurevessel while a ring groove for condensate collection can be made on thebutt of the bottom closure.

The electrically insulated heater can be either in the form of a flatinductor consisting of one-piece units of current-conducting (e.g.copper) plates, or in the form of a single-piece spiral-like copperplate. The protective magnetic block can be made of radial andnon-contiguous units of electrical steel sheet.

Due to high compressibility of the gas medium, the pressure in thevessel during gas leakage (which is more or less inevitable) is fallingnot so intensively as in the case when a liquid medium is used aspressure source, thus enabling to reduce the energy cost for maintainingthe normal technological process. Thereby any leakage of working liquidis excluded, what will have a beneficial ecological effect on theenvironment. Both the materials consumption and the dimensions of theapparatus are generally reduced.

The presence of a gas-containing volume allows to place in the vessel aheater that transfers the heat directly to the working liquid in thecontainer, and to treat the product at high temperatures. The protectivemagnetic block prevents the bottom of the working chamber from inductionheating thus allowing to reduce the convection in the gas volume and tolower the heat loss caused by the convection.

LIST OF DRAWINGS

The claimed isostatic press for treatment of materials in liquid isshown in the drawings.

FIG. 1 shows the longitudinal section of the isostatic press in workingcondition, with the feed from a high-pressure gas source (compressor).

FIG. 2 shows the enlarged heater (top view).

FIG. 3 shows the enlarged protective magnetic block (top view).

PREFERRED IMPLEMENTATION OF THE INVENTION

The isostatic press for treatment of materials in liquid comprises themulti-cylinder pressure vessel (FIG. 1) made of coaxial cylinderswhereof the outer cylinder 1 is a flat steel wire tightly wound on thesurface of the adjoining cylinder 2. The cylinders 2,3, and 4 of thepressure vessel are made in the form of one-piece metal cylinders. Inthe middle cylinder 3, the channels 5 for inlet-outlet of cooling waterare made. The inner cylinder 4 forms the working chamber 6 of thepressure vessel which is hermetically sealed by the top closure 7 andthe bottom closure 8. The closures 7 and 8 are provided with the seals9. In the working chamber 6 there is the container for liquid 10 withthe open top and the hermetically sealed bottom 11 made ofcurrent-conducting material. In the container 10 the treated material 12is placed, immersed in the working liquid 13. The hermetically sealedbottom 11 of the container 10 rests on the electrically insulated heater14 which, in its turn, rests on the protective magnetic block 15, whichis based on the upper butt of the bottom closure 8.

Between the outer surface of the container 10 and the inner surface ofthe central cylinder 4, owing to their coaxial positioning, a gap iscreated which serves as a heat-insulating envelope after the workingchamber 6 is filled with gas, thus preventing heat transfer from thewalls of the container 10 to the walls of the cylinder 4 of the pressurevessel. The gas enters the working chamber 6 of the pressure vesselthrough the pipeline 16 issuing from the compressor 17. In the butt ofthe bottom closure 8, encircling it, a ring groove 18 is made for thecondensate collection.

The electrically insulated heater 14 can be made in the form of a flatinductor consisting of units of one-piece current-conducting (e.g.copper) plates or in the form of a single-piece spiral-like copperplate. The protective magnetic block 15 (FIG. 3) is made of radial andnon-contiguous units of electrical steel sheets.

The isostatic press for treatment of materials in liquid works asfollows:

The protective magnetic block 15, the electrically insulated heater 14and the container 10 with the prepared piece of material for treatment12 immersed in the working liquid 13, are all placed in succession onthe butt of bottom closure 8 on a special device (not shown in thedrawings). The working fluid 13 is chosen according to the task to beperformed. This whole system is placed in the working chamber 6 of thepressure vessel on the bottom closure 8, and the working chamber ishermetically sealed with the help of the top closure 7 and the bottomclosure 8. The working chamber 6 is filled with a gas (or a gas mixture)using the compressor 17. Then the electrically insulated heater 14 isswitched on and the bottom of container 10 is heated ensuring the heattransfer to the treated material and the working liquid 13. Forcommercial operation, the pressure of the gas (or gas mixture) isusually chosen to be equal to, or more than, 10 MPa while a particulargas pressure value is set on the basis of specifications of the chosenliquid 13 for a particular task to be performed, and the followingnecessary condition should be met: the gas pressure should be absolutelyhigher than the critical point pressure of the liquid chosen for theprocess. E.g. for water, the critical point parameters are: pressure22.1 MPa, temperature 647 K (374° C.).

Under the applied pressure in the container 10 with the liquid 13, oneof the chosen treatment processes is taking place: densification ofdiscrete or continuous materials, curing, chemical treatment etc.

After the process has been completed, the gas pressure is brought down,the processed material is taken out of the container 10 and the processis repeated.

INDUSTRIAL APPLICABILITY

The proposed isostatic press has a broad range of technologicalcapabilities, in combination with ecological cleanness, low energy andmaterial consumption and small overall size, and it could findapplication in various industries such as powder metallurgy, polymer andrubber production etc.

What is claimed is:
 1. An isostatic press for treatment of materials ina liquid, comprising a pressure vessel, forming a hermetically sealedworking chamber connected to the pressure source, wherein an open-topcontainer for liquid is placed in such a way that a gap is createdbetween the inner wall of the pressure vessel and the outer wall of thecontainer for liquid, whereby the container for liquid has ahermetically sealed bottom made of current-conducting material and isplaced on an electrically insulated inductive heater mounted on aprotective magnetic block, while the pressure source is a gas source. 2.The isostatic press of claim 1, wherein the pressure vessel is made as amulti-cylinder unit, with coaxial tight-fitting one-piece metalcylinders whereof the outside cylinder is made of tightly woundprestressing flat steel wire.
 3. The isostatic press of clam 1, whereinthe working chamber is hermetically sealed by the top and bottomclosures with seals.
 4. The isostatic press of claim 3, wherein theprotective magnetic block is located on the top bull bottom closure. 5.The isostatic press of claim 2, wherein the apertures for inlet-outletof cooling water are made on the surface of one of the one-piece metalcylinders forming the pressure vessel.
 6. The isostatic press of claim3, wherein a ring groove for collection of the condensate is made on thebutt of the bottom closure.
 7. The isostatic press of claim 1, whereinthe inductive heater is made in the form of a flat inductor consistingof units of one-piece current-conducting (e.g. copper) plates.
 8. Theisostatic press of claim 1, wherein the heater is made of a single-piececopper plate in the form of a spiral.
 9. The isostatic press of claim 1,wherein the protective magnetic block is made of radial andnon-contiguous units of electrical steel sheets.